Continuous motion article packaging machines, such as those used in the beverage packaging industry are well-known, and various types of packaging machines are constructed to accomplish the packaging of articles into different types of cartons. One such machine enables articles, such as glass or plastic bottles, to be packaged in a basket-type carton. These cartons or baskets generally are in one of two forms. One basket has a pre-glued bottom and a locking system which engages when the collapsed carton is fully opened, and then holds the carton open so that the articles can be inserted into the open cells of the basket. For example, Riverwood International Corporation's Rough Rider 2000.TM. opening machine is used in conjunction with a basket-type drop packing machine designed to process a basket-type carton with a pre-glued base or bottom wall. The second type of basket does not have a pre-glued bottom, but instead is designed to define an opening between the side walls so that the partially assembled carton can be lowered onto a pre-configured bottle group. Once the basket is lowered around the bottle group so that the bottles are individually received within the basket side walls, flaps which initially extend from opposing side walls are folded into contact with one another to form the base of the completely assembled basket containing the articles.
Each basket-type packaging machine, including those comprised of carton opening assemblies combined with ancillary article loading devices, generally includes several similar workstations. In each machine, collapsed, partially assembled baskets are fed onto a transport mechanism by a carton pick and transfer assembly, or carton feeder. The transport mechanism then moves the collapsed cartons in continuous fashion to a carton opening assembly. During the transportation of the collapsed carton from the carton feeder to the carton opening assembly, one or more of the carton flaps, or the carton itself, may be manipulated into a desired position. At the carton opening assembly, the collapsed carton is manipulated into an opened position. At the downstream end of this workstation, the subsequent handling of the opened carton and the article loading operation differs, depending upon the type of basket packaging machine utilized. In all types of these machines, however, the result of the final workstation is a fully assembled, basket-type carton carrying the packaged articles. Such packaging machines can be comprised of a unitary device having all such workstations, or can include a series of assemblies linked together to include each such workstation.
In the Rough Rider 2000.TM. packaging machine, the collapsed carton is transported from the carton feeder on its side, and delivered to the carton opening assembly. The carton opening assembly comprises two vacuum plate assemblies which engage opposite sides of the carton, and pull the carton into a fully opened position. The carton processed by the Rough Rider 2000.TM. machine includes a pre-glued bottom wall or base with toe locks which engage the fully opened bottom wall to hold the carton or basket in a fully opened position. The basket processed by the Rough Rider 2000.TM. machine then is oriented to a handle up position, and is transported to an ancillary article loading machine which places the articles, such as bottles, into the fully opened basket. The vacuum plate assemblies of the Rough Rider 2000.TM. machine include two pairs of rotating wheels or pivots, each of which moves a vacuum plate in a circular motion at a fixed velocity. The vacuum plate transcribes a walking beam motion in which every point of the vacuum plate transcribes a circle relating to the pivot radius. Ideally, the vacuum cups of the Rough Rider 2000.TM. opening assembly will strike the carton side wall in a direction as close to vertical, or perpendicular to the side walls as possible, at which point the vacuum is applied by vacuum lines to the vacuum cups engaging the basket side wall. As the vacuum plate continues to be moved in an arc, the upper basket side wall follows that motion and ultimately is placed in a fully opened position as it continues to travel through the opening assembly on the transport conveyor. The same type of apparatus applies the same manipulation to the lower basket side wall.
In this type of opening assembly, however, there exists a speed differential due to the basket's traveling on its side in a horizontal motion or direction along the machine's longitudinal path by the transport conveyor at a fixed velocity, and the vacuum cup's moving in a circular motion, the horizontal component of which constantly changes. It is intended that the conveyed carton and the opening assembly will be at a matching speed at the moment of contact. Even if all conditions are ideal and such speed matching is accomplished, however, the vacuum cups will strike the carton side wall at an angle less than 90.degree. rather than perpendicular, which results in vacuum cup wear. A second factor associated with the Rough Rider 2000.TM.-type opening assembly, which results from the change of speed of the horizontal component of the carton side wall as it moves through the assembly in a progressively opened configuration, is that the carton tends to be opened abruptly, imparting a shock to the carton at its maximum opened position. This abrupt opening, however, is considered suitable for the Rough Rider 2000.TM.-type carton, considering that it includes a relatively stable, pre-glued base. In the Rough Rider 2000.TM. packaging machine, the maximum opening time achievable, which is a theoretical maximum, is a quarter of a cycle of the rotating pivots from the point the vacuum cups engage the carton to the point where the carton is fully opened. Typically, however, the opening time would be less than a quarter of the cycle in practical applications, as the horizontal velocity component is zero at 90.degree.. Both the above factors limit the machine's maximum speed.
A second type of basket packaging machine processes baskets without a pre-formed base or bottom wall. An example of this type of machine is Riverwood International Corporation's Autoflex 2000.TM. machine. This type of packaging machine is a basket-type machine in which the fully opened basket is lowered over the pre-configured bottle group at the article packaging workstation. That is, in this system, rather than dropping the product into the pre-formed basket, the product proceeds through the machine in a straight line, and the open-base basket is lowered over the product, with its bottom flaps thereafter glued underneath. The Autoflex 2000.TM. packaging machine also includes opposed vacuum plates, and walking beam-type opening mechanisms, which results in the same limitations as found with the Rough Rider 2000.TM. opening assembly. The Autoflex 2000.TM. packaging machine also includes servo motors to actuate the opening mechanism so that the opening cycle is more efficiently timed with the progression of the collapsed carton through the opening assembly, thus improving the performance over earlier systems.
Known basket opening mechanisms, such as those described above, however, while efficient in many respects and applications, still are limited in some respects due to the characteristics of the vacuum plate motion in the opening cycle. Additionally, some of these known opening mechanisms include a pair of drive chains that carry a series of opposed vacuum plates into engagement with unopened cartons. These chains can, however, stretch or become slack, especially with wear and extended use, causing slipping and misengaging the cartons. The chains further tend to limit the length of the opening cycle, necessitating a rapid or abrupt opening of the cartons.
There is a need in the art, therefore, for a basket-type carton opening mechanism which can accomplish more controlled basket opening over a longer period of time through a longer transport distance, and that also contacts the basket side walls perpendicularly and tracks the carton through the machine as the carton is opened. The invention of the present application presents a novel method and apparatus to overcome many of the disadvantages of prior art basket opening assemblies, and accomplishes these desired results.